Technique or method can be use to measure (the degree of impact) of the variables in the theoretical framework

In recent years, comparative research in communication science has gained considerable ground. On the one hand, this can be interpreted as a sign of communication science maturing as a research discipline. On the other hand, both in terms of quantity and quality, comparative communication research is lagging behind compared to neighboring disciplines, such as political science and sociology. In a review, specifically of comparative political communication research, Pippa Norris (2009) identifies several reasons for this, including shortage of comparative frameworks due to an overly strong focus on the United States, a lack of standardized measurement instruments, and the limited availability of large archival datasets. We expect that the unfamiliarity with the possibilities and challenges of comparative research among communication scholars also contributes to the paucity of solid comparative studies, and thus, we hope this entry fills part of this void.

More specifically, we introduce those possibilities and challenges that are particular to comparative research by drawing on the available literature from communication science and borrowing from, for example, political science literature. Focusing on the foundations and basic logic of comparative research and potential research goals, we pay ample attention to case selection, both in small‐ and large‐N studies, and to the fundamental choice between most similar and most different systems designs. A key issue in conducting comparative empirical research is to ensure equivalence, that is, the ability to validly collect data that are indeed comparable between different contexts and to avoid biases in measurement, instruments, and sampling. We introduce a typology of different types of research questions that can be addressed with comparative research, as well as the most common statistical techniques associated with those research questions. Finally, we briefly outline potentially useful theoretical frameworks and discuss how trends such as globalization alter our understanding and practice of conducting comparative research.

In many respects, the challenges to conduct solid comparative research are tremendous, as will become clear throughout this entry. However, the opportunities are equally tremendous, especially in a time when archival data have become increasingly accessible digitally and when comparative datasets that are of particular interest to communication scholars are collected and made publicly available. As comparative research offers the opportunity to address a particular set of questions that are of crucial importance for our understanding of a wide range of communicative processes, it deserves a central position in communication science.

Comparative research in communication and media studies is conventionally understood as the contrast among different macro‐level units, such as world regions, countries, sub‐national regions, social milieus, language areas and cultural thickenings, at one point or more points in time. A recent synthesis by Esser and Hanitzsch (2012a) concluded that comparative communication research involves comparisons between a minimum of two macro‐level cases (systems, cultures, markets, or their sub‐elements) in which at least one object of investigation is relevant to the field of communication. Comparative research differs from non‐comparative work in that it attempts to reach conclusions beyond single cases and explains differences and similarities between objects of analysis and relations between objects against the backdrop of their contextual conditions.

Generally speaking, comparative analysis performs several important functions that are closely interlinked. More specifically, comparative analysis enhances the understanding of one's own society by placing its familiar structures and routines against those of other systems (understanding); comparison heightens our awareness of other systems, cultures, and patterns of thinking and acting, thereby casting a fresh light on our own political communication arrangements and enabling us to contrast them critically with those prevalent in other countries (awareness); comparison allows for the testing of theories across diverse settings and for the evaluating of the scope and significance of certain phenomena, thereby contributing to the development of universally applicable theory (generalization); comparison prevents scholars from over‐generalizing based on their own, often idiosyncratic, experiences and challenges claims to ethnocentrism or naïve universalism (relativization); and comparison provides access to a wide range of alternative options and problem solutions that can facilitate or reveal a way out of similar dilemmas at home (alternatives).

In addition to these general benefits, comparison also has specific scientific advantages. To fully exploit these benefits, it is essential that the objects of analysis are compared on the basis of a common theoretical framework and that this is performed by drawing on equivalent conceptualizations and methods. It is further noted that spatial (cross‐territorial) comparisons should be supplemented wherever possible by a longitudinal (cross‐temporal) dimension to account for the fact that systems and cultures are not frozen in time; rather, they are constantly changing under the influence of transformation processes, such as Americanization, Europeanization, globalization, modernization, or commercialization. Combining cross‐sectional and longitudinal designs helps to understand these transformation processes and makes clear that different contexts affect the results in different ways.

What distinguishes comparative research from simple border‐transgressing kinds of (international/transnational) research is that comparativists carefully define the boundaries of their cases. This can be accomplished in a variety of ways based on structural, cultural, political, territorial, functional, or temporal qualities. Thus, it is not only territories that can be compared. That said, if territories are compared, the comparison can occur at many levels above and below the nation‐state and can incorporate other relevant social, cultural, and functional factors. Macro‐level cases, however defined, are assumed to provide characteristic contextual conditions for a certain object that is investigated across cases. Different contextual conditions (=factors of influence) are used to explain different outcomes regarding the object under investigation (=embedded in these contexts and hence affected by them), while similar contextual conditions are used to explain similar outcomes. The corresponding research logic of Most Similar Systems Design and Most Different Systems Design is introduced and explained herein.

It is crucial to understand this basic logic of comparative research. Comparative research guides our attention to the explanatory relevance of the contextual environment for communication outcomes and aims to understand how the systemic context shapes communication phenomena differently in different settings. The research is based on the assumption that different parameters of political and media systems differentially promote or constrain communication roles and behaviors of organizations and actors within those systems. Thus, comparativists often use factors at the macro‐societal level as explanatory variables for differences found in lower level communication phenomena embedded within the societies. Additionally, macro‐level factors are considered moderators that influence relationships between variables at the lower level. This recognition of the (causal) significance of contextual conditions is why comparative research is so exceptionally valuable. In the words of Mancini and Hallin, “theorizing the role of context is precisely what comparative analysis is about” (2012, p. 515). This explanatory logic can be distinguished from a mere descriptive comparison that is considered less mature, and it also extends clearly beyond the general advantages of comparison as outlined before and constitutes the status of comparative analysis as a separate and original approach.

Overall, there are several conditions that should be fulfilled before labeling a comparison as a mature comparative analysis. First, the purpose of comparison must be explicated early in the project, and it should be a defining component of the research design. Second, the macro‐level units of comparison must be clearly delineated, irrespective of how the boundaries are defined. In the contextual environments, specific factors that are assumed to characteristically affect the objects of analysis—be they people, practices, communication products or other structural or cultural elements—must be identified. Third, the objects of analysis should be compared with respect to at least one common, functionally equivalent dimension. Methodologically, an emic (culture‐specific) or etic (universal) approach may be applied. Fourth, the objects of analysis must be compared on the basis of a common theoretical framework and must draw on equivalent conceptualizations and methods rather than be analyzed separately. These elements will be further discussed in the sections that follow.